Question: Who was the spouse of Fyodor Tyutchev until August 27, 1838?
Paraphrase: Who was Fyodor Tyutchev's spouse prior to August 1838?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q37217 p:P26 ?s . ?s ps:P26 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'1838')) }